Photographic silver halide emulsions

ABSTRACT

A PHOTOGRAPHIC SILVER HALIDE EMULSION WHICH CONTAINS A NOVEL SENSITIZING DYE REPRESENTED BY THE FOLLOWING FORMULA F WHEREIN Z REPRESENTS THE NON-METALLIC ATOMS NECESSARY TO COMPLETE A HETEROCYCLIC RING OF THE TYPE EMPLOYED IN A CYANINE DYE; R AND R1 EACH REPRESENT A MEMBER SELECTED FROM THE GROUP CONSISTING OF A LOWER ALKYL GROUP, A SUBSTITUTED ALKYL GROUP, AN ALLYL GROUP, A BENZYL GROUP, A PHENETHYL GROUP AND A PHENOXYETHYL GROUP; X-REPRESENTS AN ANION; N MAY VARY FROM 0 TO 1 ; N1 MAY VARY FROM 0 TO 1; AND M MAY VARY FROM 1 TO 2. THE VARIOUS SPECIFIC DYES AND ILLUSTRATIVE PROCESSES OF FORMING THE DYES OF THIS INVENTION ARE DESCRIBED IN THE SPECIFICATION.

United States Paten 3,556,800 PHOTOGRAPHIC SILVER HALIDE EMULSION SShiro Kimura, Yoshiyuki Nakazawa, Masao Sawahara, and Yasuharu Nakamura,Kanagawa, Japan (all of 210 Nakanuma, Minami Ashigara-machi,Ashigara-Kamigun, Japan) No Drawing. Filed July 25, 1968, Ser. No.747,480 Claims priority, application Japan, July 25, 1967, 42/47,721Int. Cl. G03c 1/08 US. Cl. 96-120 2 Claims ABSTRACT OF THE DISCLOSURE Aphotographic silver halide emulsion which contains a novel sensitizingdye represented by the following formula and illustrative processes offorming the dyes of this invention are described in the specification.

BACKGROUND OF THE INVENTION Field of the invention The present inventionrelates generally to a photographic silver halide emulsion, and moreparticularly, to a photographic silver halide emulsion containing anovel cyanine sensitizing dye in which a benzene ring forming thequinoline nucleus has a fluorine atom as a substituent.

Description of the prior art It is known, in the art of preparingphotographic silver halide emulsions, that by incorporating asensitizing dye in a photographic silver halide emulsion, thelight-sensitive wave length spread of the silver halide emulsion can beincreased, i.e., the silver halide emulsion can be spectrallysensitized.

However, the incorporation of a sensitizing dye in a light-sensitivesilver halide emulsion tends to increase the formation of photographicfog in the photographic emulsion layer, especially, when a sensitizingdye having a quinoline nucleus is employed.

SUMMARY OF THE INVENTION It has been found that when a photographicsilver halide emulsion has incorporated therein a sensitizing dyerepresented by the following general formula:

I R-N -en =cnon) n:oon=on) h n.

wherein Z represents the non-metallic atoms necessary to complete aheterocyclic ring of the type employed in a cyanine dye; R and R eachrepresent a member selected Patented Jan. 19 1971 from the groupconsisting of a lower alkyl group, a substituted alkyl group, an allylgroup, a benzyl group, a phenethyl group and a phenoxyethyl group; X-represents an anion; 11 may vary from 0 to 1; n may vary from 0 to l;and in may vary from 1 to 2.

The novel sensitizing dye of the present invention can spectrallysensitize a silver halide emulsion, and, in particular, it is quiteeffective in enlarging the spectral lightsensitive region of a gelatinosilver halide emulsion.

An object of this invention is to provide a novel sensitizing dye havinga quinoline nucleus.

Another object of this invention is to provide a lightsensitive silverhalide emulsion, containing the novel sensitizing dye mentioned above,will well illustrate reduced fogging.

DESCRIPTION OF THE PREFERRED EMBODIMENT The aforesaid objects of thisinvention can be attained by incorporating in a photographic silverhalide emulsion a sensitizing dye represented by general Formula Iwherein R and R each may represent: lower alkyl group, such as a methylgroup, an ethyl group, a propyl group, and a butyl group; a substitutedalkyl group, such as a 2-hydroxyethyl group, a 2-acetoxyethyl group, a3-hydroxypropyl group, a carboxymethyl group, a 2-carboxy ethyl group, a3-carboxypropyl group, a 2-sulfoethyl group, a 3-sulfopropyl group, a4-sulfobutyl group and the like; an allyl group; a benzyl group; aphenethyl group; or a phenoxyethyl group; Z represents the nonmetallicatoms necessary to complete a heterocyclic ring of the type' usuallypresent in a cyanine dye, such as, a thiazole ring, a benzothiazolering, a naphthothiazole ring, an oxazole ring, a benzoxazole ring, anaphthoxazole ring, a selenazole ring, a benzoselenazole ring, anaphthoselenazole ring, a thiazoline ring, anoxazoline ring, aselenazoline ring, a thiadiazole ring, an indolenine ring, a pyridinering, a 2-quinoline ring, a 4-quin0line ring, or a benzoimidazole ring;X represents an anion such as a chlorine ion, a bromine ion, an iodineion, a perchloric acid ion, a p-toluenesulfonic acid ion, or an ethylsulfate ion; n is 0, 1, or 2; and m is 1 or 2; said dye forming anintramolecular salt when m is 1.

The sensitizing dye used in this invention may be prepared by knowncondensation methods using the compound (Compound II) shown by generalFormula II wherein R and X" have the same meaning as heretofore defined.When R and X contain sulfonic acid or carboxylic acid, the compound mayhave a betaine structure by intermolecular ionization, or the compoundmay be an alkali metal salt.

Compound II may be prepared by reacting fluoroanilines and methylvinylketone using general methods of preparing 4-methylquinolines. Theproduct may then be converted into its quaternary salt.

Practical methods of preparing the sensitizing dyes of this inventionwill be explained below.

(1) Preparation of 8-fluoro-4-methylquinoline:

Into a 1-liter three-necked flask equipped with a liquidsealedmechanical stirrer, a reflux condenser, a thermometer and a droppingfunnel, there Were charged 150 g. of o-fluoroaniline, 95 g. of methylvinyl ketone and 145 ml. of nitrobenzene. This was then diluted withsulfuric acid (concentrated sulfuric acid: 45 ml., and water: 22 ml.)which was added thereto dropwise. When heat was generated in themixture, the temperature thereof rose to about 100 C. Thereafter, thesystem was. stirred for 2 hours at 100-105 C. in an oil bath to completethe reaction. After the reaction was finished, 300 ml. of water Wasadded to the product, and the mixture was then subjected to a steamdistillation to distil ofi nitrobenzene. The residue was cooled, madealkaline by the addition of 100 g. of sodium hydroxide, extracted withbenzene, and dried -With potassium carbonate. After removing benzene bya distillation, the residue was subjected to a reduced-pressuredistillation, whereby fractions having a boiling point in the range of137145 C./7 mm. Hg were collected. The product obtained was dissolved in100 ml. of isopropanol by heating, and when the solution obtained wascooled by the addition of ice, 50 g. of the crystals of8-fluoro-4-methylquinoline were obtained. The melting point of thecrystals was 5658 C.

(2) Preparation of 6-fluoro-4-methylquinoline:

Into a 500 ml. three-necked flask equipped with a liquid-sealedmechanical stirrer, a reflux condenser, a thermometer and a droppingfunnel, there were charged 90 g. of p-fluoroaniline, 57 g. of methylvinyl ketone, and 100 ml. of nitrobenzene. This was then diluted withsulfuric acid (concentrated sulfuric acid: 35 ml.; water: ml.) which wasadded dropwise thereto. The system was then processed as in the aboveexample (No. 1) to provide 28 g. of the crystals of6-fluoro-4-methylquinoline, having a boiling point of 134136 C./l9 mm.Hg.

(3) Preparation of 1-ethyl-8-fluoro-4-methylquin0linium iodide:

A mixture of 4 g. of 8-fluoro-4-methylquinoline and 6 g. of ethyl iodidewas refluxed under heat for 20 hours. After cooling, the product wasmixed with acetone and filtered to provide 7 g. of the iodide of thequinoline, having a melting point of 153155 C.

(4) Preparation of 1-ethyl-6-fluoro-4-methylquinolinium iodide. Thebasic procedures outlined above (No. 3) Were followed:

Cir

(5) Preparation of l-ethyl-8-fiuoro-4-methylquinoliniump-toluenesulfonate: A mixture of 30 g. of 8-fluoro-4- methylquinolineand 42 g. of ethyl p-toluenesulfonate was heated to 140 C. for 4 hoursin an oil bath. After cooling, the product was mixed with acetone andthe mixture was stirred to form crystals, which were recovered byfiltration. 62 g. of the crystals of the iodide having a melting pointof 123-125 C. were obtained.

(6) Preparation of 1-ethyl-6-fluoro-4-rnethylquino1iniump-toluenesulfonate:

A mixture of g. of 6-flu0r0-4-methylquinoline andethyl-p-toluenesulfonate was heated to 140 C. for 4 hours in an oilbath. After cooling, the product was mixed with ether and acetone,stirred and filtrated to provide g. of the hygroscopic crystal of thesulfonate.

(7) Preparation of 4-(2-acetanilidovinyl)-1-ethyl-8 fluoroquinoliniump-toluenesulfonate:

COCH3 A mixture of g. of 1-ethyl-8-fiuoro-4-methylquinoliniump-toluenesulfonate and 35 g. of diphenyl formamidine was heated to C.for 10 minutes in an oil bath with intermittent stirring. After cooling,the product was mixed with acetone and the precipitates formed wererecovered by filtration and boiled in acetone to provide 38 g. of thecrystal of 4-(2-anilinovinyl)-1-ethyl-8- fluoroquinoliniump-toluenesulfonate, having a melting point of 192-193 C. The product (35g.) and 200 ml. of acetic anhydride were heated for 8 minutes to C. inan oil bath. After cooling, the product was mixed with ether and theprecipitate formed was recovered by filtration and washed with ether toprovide 35 g. of the crystals of the sulfonate, having a melting pointof 12S 127 C.

(8) Preparation of 4-(2-anilinovinyl)-1-ethyl-6-flu0roquinoliniump-toluenesulfonate:

A mixture of 30 g. of 1-ethyl-6-fiuor0-4-methylquinoliniump-toluenesulfonate and 19.5 g. of diphenyl formamidine was heated to 140C. for 10 minutes in an oil bath, with intermittent stirring. Aftercooling, the prod uct Was mixed with ether and acetone to causecrystallization, and the precipitate formed was recovered by filtration,washed with acetone and recrystallized from a mixed solvent of methanoland isopropanol to provide 11.5 g. of the sulfonate, having a meltingpoint of 218220 C.

(9) Preparation of 1,3'-diethyl-8-fluorothia-4-cyanine iodide:

A mixture of 2.8 g. of 1-ethyl-8-fluoro-4-methylquinoliniump-toluenesulfonate and 2 g. of 3-ethyl-2- methylthiobenzothiazoliumethyl sulfate was dissolved in 60 ml. of ethanol by heating. Afteradding 4 ml. of triethylamine, the mixture was boiled for 30 minutesunder conditions of reflux. After the reaction was finished, an aqueoussolution of potassium iodide was added to the system, precipitating thedye. After cooling, the percipitate was recovered by filtration, washedwith water, and recrystallized (twice) from a mixed solvent of methanoland chloroform to provide 1.9 g. of the dye, having a melting point of281-282 C. (decomposed). The absorption maximum of the dye, in methanol,was 508 m (10) Preparation of l,1-diethyl-8,8 difluoro-4,4- carbocyanineiodide:

A mixture of 4 g. of 1-ethyl-8-fluoro-4amethylquinolinium, 8 ml. ofethyl o-formate, and 1 ml. of triethylamine was boiled for 3 minuteswith refluxing. After the reaction was finished, the dye thus formed wasrecovered by filtration, washed with acetone and recrystallized (twice)from a mixed solvent of methanol and chloroform to provide 0.8 g. of thedye, having a melting point of 276-277 C. (decomposed). The absorptionmaximum of the dye in methanol was 709 mg.

(11) Preparation of 1,1' diethyl-8-fluoro-2',4-carbocyanine iodide:

Into 120 ml. of ethanol were dissolved, by heating, 3 g. ofl-ethyI-S-fluoro-4-methylquinolinium p-toluenesulfonate and 2.9 g. of2-(2 acetanilidovinyl) l-ethylquinolinium iodide. The solution was thenmixed with ml. of triethylamine and the mixture was boiled, withrefluxing for 30 minutes. After the reaction was finished,

the dye thus formed was filtered, washed with ethanol and recrystallizedfrom a mixed solvent of methanol and chloroform to provide 1.9 g. of thedye having a melting point of 258-259 C. (decomposed). The maximumabsorption maximum of the dye in methanol was 656 my.

(12) Preparation of 1,3 diethyl8-fluoro-5',6-dimethylthia-4-carbocyanine iodide:

Into 50 ml. of ethanol were dissolved, by heating, 1 g. of4-(2-acetanidovinyl) 1-ethyl-8-fluoroquinolinium p-toluenesulfonate and0.66 g. of 3-ethyl-2,5,6-trirnethylbenzothiazolium iodide. After theaddition of 3 ml. of tri ethylamine to the solution, the mixture wasrefluxed for 30 minutes. After the reaction was finished, the dye thusprecipitated was recovered by filtration, washed with ethanol andrecrystallized from a mixed solvent of methanol and chloroform toprovide 0.9 g. of the dye having a melting point of 266267 C.(decomposed). The absorption maximum of the dye in methanol was 651III/1..

(13) Preparation of 6',7 benzo 1,3'-diethy1-6- fluorothia-4-carbocyaninep-toluenesulfonate:

A mixture of 2 g. of l-ethyl-6-fluoro-4-methylquinoliniump-toluenesulfonate, 1.6 g. of 2-(2-anilinovinyl)-3- ethyl-naphtho[2,1-a] thiazolium p-toluenesulfonate, ml. of ethanol, and 6 ml. ofacetic anhydride was heated with the addition of 5 ml. of triethylamineand the mixture was refluxed for one hour. After the reaction wasfinished, the product was concentrated, cooled and mixed with ether, andthe dye thus precipitated was filtered and recrystallized from a mixedsolvent of ethanol, chloroform and isopropanol (three times) to provide1.3 g. of the dye, having a melting point of 259 C. (decomposed). Theabsorption maximum of the dye in methanol was 660 m (14) Preparation of1,3'-diethyl 8 fluoro-5,6-dimethylselena-4-carbocyanine iodide:

Into 70 ml. of ethanol were dissolved 1 g. of 4-(2- acetanilidovinyl)1-ethyl-8-fluoroquinolinium p-toluenesulfonate and 0.75 g. of 3ethyl-2,5,6-trimethylbenzoselanazolium iodide. After adding 4 ml. oftriethylamine, the mixture was refluxed for 30 minutes. After thereaction was finished, the dye thus formed was filtered andrecrystallized from a mixed solvent of methanol and chloroform toprovide 0.8 g. of the dye, having a melting point of 266-267" C. Theabsorption maximum of the dye in methanol was 657 mp.

(15) Preparation of anhydro 6,7 benzo-3-ethyl- 8-fluoro-l(3sulfopropyl)thio 4 carbocyanine hydroxide:

A mixture of 2 g. of 8-fluoro-4-methylquinoline and 2.3 g. of propanesulfone was heated to -160 C. for 2 hours in an oil bath. After thereaction was finished, acetone was added to the product with stirring tocause crystallization and the crystals thus formed were filtered andwashed with ethanol to provide 2.2 g. of anhydro-S- fluoro-4-methyl-1(3-sulfopropyl)-quinolinium hydroxide. A mixture of 0.7 g. of theproduct, 150 ml. of 2- (2-anilinovinyl) 3 ethylnaphtho [2,1-a]thiazolium p-toluenesulfonate, 150 ml. of ethanol, and 3 ml. of aceticanhydride was heated, and, after adding ml. of triethylamine, theresulting mixture was refluxed for 30 minutes. After the reaction wasfinished, the dye thus precipitated was filtered and recrystallized froma mixed solvent of acetic acid and pyridine to provide 0.5 g. of the dyehaving a melting point of 300 C. (decomposed). The absorption maximum ofthe dye in methanol was 663 mg.

(16) Preparation of anhydro-6,7' benzo 3'-carboxy-methyl 1ethyl-8-fluorothia-4-carbocanine hydroxide:

A mixture of 2.5 g. of 4-(2-acetanilidovinyl)-l-ethyl-8-fluoro-quinolinium p-toluenesulfonate, 1.65 g. of3-carboxyrnethyl-Z-methylnaphtho [2,1-a]thiazolium bromide, and 100 ml.of ethanol was heated, and after the addition of 4 ml. of triethylamine,the resulting mixture was refluxed for 30 minutes. After the reactionwas finished, the product was concentrated, cooled and mixed with etherwhile stirring. After removing the ether layer which formed bydecantation, a small amount of isopropanol and ether was added toprecipitate the dye, which was filtered and recrystallized from a mixedsolvent of methanol and chloroform to provide 1.1 g. of dye having amelting point of 193-194 C. (decomposed). The absorption maximum of thedye in methanol was 662 m (17) Preparation of 6,7'-benzo'-carboxyethyl-1- ethyl-8-fluorothia-4-carbocyanine bromide:

A mixture of 2 g. of 4-(Z-acetanilidovinyl)-1-ethyl-8 fluoro-quinoliniump-toluenesulfonate, 1.3 g. of 3-carboxyethyl-Z-methylnaphtho [2,l-oc]thiazolium bromide, and 50 ml. of ethanol was heated, After adding 2 ml.of triethylamine, the mixture Was refluxed for 3 minutes. After thereaction was finished, the product was concentrated, cooled, and mixedwith ether to precipitate the dye, which was filtered and recrystallized(twice) from a mixed solvent of methanol and chloroform to provide 1.5g. of dye having a melting point of 203205 C. (decomposed). Theabsorption maximum of the dye in methanol was 662 my.

(18) Preparation of anhydro-6,7'-benzo-l-ethyl-6- fluoro-3 3-sulfopropylthia-4-carbocyanine hydroxide:

ro-quinolinium p-toluenesulfonate, 0.69 g. of anhydro-Z-1nethyl-3-(3-sulfopropyl) naphtho[2,1a]thiazolium hydroxide, 200 ml. ofethanol, and 4 ml. of acetic anhydride was heated, and, after adding 5ml. of triethylamine, the mixture was refluxed for 30 minutes. After thereaction was finished, the dye thus formed was filtered andrecrystallized from a mixed solvent of acetic acid and pyridine toprovide 0.8 g. of dye having a melting point above 300 C. (decomposed).The absorption maximum of the dye in methanol was 663.5 m

(19) Preparation of 6',7-benzo-l-(3-carboxypropyl)-3-ethyl-8-fluorothia-4-carbocyanine bromide:

A mixture of 5 g. of 8-fluoro-4-methy1quinoline and 4.6 g. ofa-butylonitrile was heated to 140 C., for 6 hours, in an oil bath. Afterreaction was completed, the product was cooled, mixed with ether andacetone with stirring to cause crystallization. The crystals thus formedwere recovered by filtration and recrystallized from a mixed solvent ofethanol and isopropanol to provide 3.6 g. of 1-(3-cyanopropyl) 8fluoro-4-methylquinolinium bromide, having a melting point of 180-181 C.The product (3.6 g.) was then refluxed for 6 hours with ml. ofhydrobromic acid (48%), concentrated under reduced pressure and cooledto cause crystallization. The crystals thus formed were filtered toprovide 2.5 g. of 1-(3-carboxypropyl) 8 fluoro 4 methylquinoliniumbromide. A mixture of 1.2 g. of the product, 1.5 g. of 2-(2-anilinovinyl) 3 ethyl 6,7 benzobenzothiazolium p-toluenesulfonate,150 ml. of ethanol, and 4 ml. of acetic anhydride was heated, and, afteradding 5 ml. of triethylamine, the mixture was refluxed for 30 minutes.After the reaction was finished, the product was concentrated, cooled,and mixed with ether to cause crystallization. The dye thus formed wasfiltered and recrystallized (twice) from a mixed solvent of methanol andisopropanol to provide 0.6 g. of the crystals of dye having a meltingpoint of 193-195 C. The absorption maximum of the dye in methanol was662 m Preparation of 1,3'-diethyl-8-fluorothia-4-dicarbocyanine iodide:

Into 150 ml. of ethanol there were dissolved, by heating, 2.8 g. of1-ethyl-8-fluoro-4-methylquinolinium p-tolucnesulfonate and 2.6 g. of2-(4-acetanilido-1,3-butadienyl)-3-ethylbenzothiazoliurn iodide. Afteradding 4 ml. of triethylamine, the mixture was refluxed for minutes.After the reaction was finished, the product was cooled and the dye thusformed was obtained by filtration and recrystallized from a mixedsolvent of methanol and chloroform to provide 1.6 g. of dye having amelting point of 214-215 C. The absorption maximum of the dye inmethanol Was 736.5 m

In addition to the aforesaid sensitizing dyes, the following dyes arewithin the scope of the present invention and it is believed that thepreparation of these dyes will be easily Understand fmm Hm aimm mmtmn..--..1.

Dye 21-6,7 benzo-l,3'-diethyl-8-fluorothia-4-carbocyanine iodide:

Melting point 266 C. (decomposed); absorption maximum 660 mg. (inmethanol).

Dye 221,3-diethyl 5 ethoxy 8 fluoro 6- rnethylthia-4-carbocyanlneiodide:

Melting point 264 C. (decomposed); absorption maximum 660 ITl/L. (inmethanol).

Dye 23-Anhydro 1 ethyl 5,6' dimethyl 8- fluoro 3' (3-sulfopropyl)selena4 carbocyanine hydroxide:

Melting point 297 C. (decomposed); absorption maximum 658.5 mg (inmethanol).

Dye 24anhydro-1-ethyl-5,6'-dimethyl-8-fluoro-3'-(3- sulfopropylthiacarbocyanine hydroxide Melting point 298 C.; absorption maximum 652mp. (in methanol).

The novel sensitizing dye used in this invention can spectrallysensitize a silver halide emulsion, and, in particular, is quiteelfective for enlarging the spectral lightsensitive region of a gelatinosilver halide emulsion.

The sensitizing dye of this invention will also sufficiently sensitize aphotographic emulsion containing hydrophilic colloids other thangelatin, such as agar agar, collodon, water-soluble cellulosederivatives, polyvinyl alcohol and other synthetic or naturalhydrophilic resins.

In the silver halide emulsion of this invention, there may be employedvarious silver salts, such as, silver chloride, silver bromide, silveriodo-bromide, silver chlorobromide, silver chloroido-bromide, and thelike.

The sensitizing dye of this invention may also be added to aphotographic silver halide emulsion which has been preliminarilysensitized by a physical ripening or a chemical ripening.

To prepare the sensitized photographic silver halide emulsion of thisinvention, one or more sensitizing dyes of this invention may beincorporated in a photographic emulsion by conventional methods. Inpractice, the sensitizing dye is incorporated into the photographicemulsion as a solution in a suitable solvent, such as methanol orethanol. The amount of the sensitizing dye may be widely varied. Formost commercial purposes, a range of 1-150 mg. of dye per one kg. ofemulsion, according to the final use, will be acceptable.

The photographic silver halide emulsion of this invention, containingthe sensitizing dye, may be further subjected to super-sensitization andhyper-sensitization, if desired.

In the preparation of the silver halide emulsion of this invention,additives that are usually employed in the field, such as, sensitizers,stabilizers, color toning agents, hardening agents, surface activeagents, antifoggants, plasticizers, developing accelerators, couplers,and fluorescent whitening agents may be incorporated into thephotographic silver halide emulsion.

In addition, when the silver halide emulsion of this invention alsocontains at least one of the following materials: Compound A-I, CompoundA-II, Compound A- III or Compound B, described in Japanese patentpublication No. 4,724/53, Japanese patent application No. 11,- 669/ 67,Japanese patent application No. 52,488/65, and Japanese patentpublication No. 81,697/ 65, respectively, the sensitivity of thespectral sensitizing regions can be increased. That is, asuper-sensitizing effect can be obtained, and further, the spectralsensitivity decrease during preservation of light sensitive elementshaving the light-sensitive layers of the silver halide emulsions of thisinvention can be halted to a great extent.

Compound A-I is represented by the general formula:

I I X X wherein R and R each may represent a hydrogen atom, an alkylgroup, an aryl group, an aralkyl group, an acyl group, an alkoxyl group,an unsubstituted or substituted carbamyl group, a hetercyclic ring; andX and X each represent a hydrogen atom or SO I-I.

Compound A-II is represented by the following general formula:

Compound AIII is represented by the following general formula:

wherein R and R each represents a halogen atom, a hydroxyl group, or NHR(where R represents an aryl group or an aralkyl group); D represents ahydogen atom, an alkali metal, an ammonium group or an amine salt.

1 1 Compound B is a condensation product of formaldehyde and a compoundrepresented by the following formula:

The sensitizing dyes of this invention were incorporated in a silverchlor-bromide emulsion (AgBr 40 moles; AgCl 60 moles). The photographicemulsion thus prepared was applied to a cellulose triacetate film anddried to provide a light-sensitive film. The light sensitive emulsionlayer was exposed to the light of a tungsten lamp, using a diffractiongrating spectrograph, developed. The spectral sensitivitycharacteristics were then measured. During the development, a developerhaving the composition shown below (Table 1) was used:

TABLE 1 G. N-methyl-p-aminophenol sulfate 20 Hydroquinone 4.0 Sodiumcarbonate (anhydrous) 24 Potassium bromide 1 Sodium sulfite 40 Water tomake In Table 2, the sensitization maximums of each of the sensitizingdyes of this invention are shown when each dye was added to thephotographic emulsion described above.

Table 3 shows the results of a comparison of the fog densities whenemploying the silver halide emulsions of this invention and whenemploying identical silver halide emulsions containing the conventionalsensitizing dyes shown below (not the novel dyes of the presentinvention).

TABLE 2 Sensitization sensitizing dye Amount* Ag halide maximum, my

0.03 AgCl/Br 530 0.006 AgGl/Br 690 0.006 AgCl/Br 675 0.006 AglC/Br 0800.006 AgCl/Br 680 0.006 AgCl/Br 690 0.006 AgCl/Br 685 0.006 AgCl/Br 6800.006 AgCl/Br 685 0.006 AgCl/Br 685 0. 006 AgCl/Br 685 0.006 AgCl/Br 6850.006 AgCl/Br 690 0.006 AgCl/Bl' 675 The conventional sensitizing dyes(comp) used in the above experiments are shown below:

| C3115 What is claimed is: 1. A photographic silver halide emulsioncontaining a sensitizing dye represented by the general formula whereinZ represents the non-metallic atoms necessary to complete a heterocyclicring of the type employed in a cyanine dye; R and R each represents amember selected from the group consisting of a lower alkyl group, asubstituted alkyl group, an allyl group, a benzyl group, a phenethylgroup and a phenoxyethyl group; X- represents an anion; u may vary from0 to 1; 11 may vary from 0 to l; and in may vary froml to 2.

2. The photographic silver halide emulsion claimed in claim 1 whereinsaid sensitizing dye is selected from the group consisting of8-fluoro-4-methylquinoline; 6-fluoro-4-methylquinoline;1-ethyl-8-fluoro-4-methylquinolinium iodide;1-ethyl-6-fluoro-4-methyl-quinolinium iodide;1-ethyl-8-fiuoro-4-methylquinolinium p-toluenesulfonate;1-ethyl-6-fluoro-4-methylquinolinium p-toluenesulfonate; 4-Z-acetanilidovinyl) l -ethyl-8-fluoro-quinolinium p-toluenesulfonate;4-(Z-anilinovinyl)-1-ethyl-6-fluoro-quinolinium n-toluenesnlfnmrp- 131,1'-diethy1-8,8'-difiuoro-4,4'-carb0cyanine iodide;1,1-diethy1-S-fluoro-Z,4-carbocyanine iodide; 1,3'-diethy1-8-fiuoro-5',6'-dimethy1thia-4-carbocyanine iodide;6,7-benzo-1,3'-diethy1-6-fluor0thia-4-carbocyanine p-toluenesulfonate;1,3-diethyl-8-fluoro-5',6-dimethy1selena-4-carbocyanine iodide;anhydro-6',7-benzo-3'-ethyl-8-fiuoro-1-(3-su1fopropy1)thia-4-carbocyanine hydroxide;anhydro-6,7-benZo-3'-carboxymethy1-1-ethy1-8- fluorothia-4-carbocyaninehydroxide; 6,7'-ben2o-3'-carboxyethy1-1-ethy1-8-fluorothia-4-carbocyanine bromide; anhydro-6,7'-benzo-1-ethy1-6-fiuoro-33-sulfopropy1) thia-4-carbocyanine hydroxide;6',7'-benzo-1-(3-carboxypropy1)-3-ethyl-8-fluoro-thia-4- carbocyaninebromide; 1,3'-diethyl-8-fiuorothia-4-dicarbocyanine iodide;6,7'-benzo-1,3'-diethyl-8-fluorothia-4-carbocyanine 14 iodide;1,3-diethy1-5'-ethoxy-8-fluoro-6-methy1thia-4- carbocyanine iodide;anhydro-1-ethyl-5',6-dimethy1-8-fluoro-3'-(3-sulfopropy1)selena-4-carbocyanine hydroxide; andanhydro-l-ethy1-5',6-dimethyl-8-fluoro-3'-(S-sulfopropyl)thia-4-carbocyanine hydroxide.

References Cited UNITED STATES PATENTS 2,912,329 11/1959 Jones et a1.96--106 NORMAN G. TORCHIN, Primary Examiner E. C. KIMLIN, AssistantExaminer US. Cl. X.R. 96-106

